| 摘要 |
PURPOSE:To improve corrosion resistance by consisting the brazed parts between the outside pipe part and inside pipe part of a pipe and the surface layer parts of both inside and outside surfaces of the pipe essentially of Fe, Cu, Ni and making the content of Fe on the steel base side and the contents of Fe, Ni on the opposite side lower the further from the steel base. CONSTITUTION:Plated steel plates are double wound and are brazed by melting the plating coated layers on the top surfaces of the steel plates, whereby a double wound pipe produced. More specifically, Ni plating of 0.1-5mu thicknesses is carried out on both front and reat surfaces of steel plates or stainless steel plates, and Cu plating of 0.5-10mu thicknesses is carried out thereon. Two sheets of such steel plates or stainless steel plates are superposed and are made into a double wound pipe, and this pipe is subjected to a brazing treatment. The above- mentioned plating may be any of electroplating, chemical plating and vapor phase plating. |
